Flexoelectricity is a property of a dielectric material where there is coupling between electrical polarization and a strain gradient.
This phenomenon is closely related to piezoelectricity, but while piezoelectricity refers to polarization due to uniform strain, flexoelectricity specifically involves polarization due to strain that varies from point to point in the material.
This nonuniform strain breaks centrosymmetry, meaning that unlike in piezoelectricity, flexoelectric effects occur in both centrosymmetric and asymmetric crystal structures.
It plays a critical role in explaining many interesting electromechanical behaviors in hard crystalline materials and core mechanoelectric transduction phenomena in soft biomaterials.
[3] In common usage, flexoelectricity is the generation of polarization due to a strain gradient; inverse flexoelectricity is when polarization, often due to an applied electric field, generates a strain gradient.